Electrical inductance and method

ABSTRACT

An electrical inductance is formed from a coil form provided with a pair of axially aligned, spaced-apart generally U-shaped slits which provide a pair of tabs foldable outwardly for use in anchoring the wire. A plurality of turns of wire are wound about the coil form over the opening provided by one outwardly folded tab, and the wire is then turned around the first tab and then around the other tab. A strip of tape is then laid down over the tabs and therebetween to anchor the wire in place during extraction to provide an internal lead for the inductance.

United States Patent Inventor Edwin C. Rechel 85 Lancaster Road, Shlrley, Mass. 01464 Appl. No. 088,654 Filed Nov. 12, 1970 Patented Sept. 28, 1971 ELECTRICAL INDUCTANCE AND METHOD 5 Claims, 4 Drawing Figs.

US. Cl 336/192, 29/605 Int. Cl ..1-10lf 15/10, HOlf 41/00 Field of Search 336/192; 29/602, 605

References Cited UNITED STATES PATENTS 1,723,261 8/1929 Varley 336/192X 2,779,928 [/1957 Jeffery 336/192 3,277,417 10/1966 Rechel 336/192 3,518,596 6/1970 Connell 336/192 Primary Examiner-Thomas J. Kozma AttorneyDawson, Tilton, Fallon & Lungmus ABSTRACT: An electrical inductance is formed from a coil form provided with a pair of axially aligned, spaced-apart generally U-shaped slits which provide a pair of tabs foldable outwardly for use in anchoring the wire. A plurality of turns of wire are wound about the coil form over the opening provided by one outwardly folded tab, and the wire is then turned around the first tab and then around the other tab. A strip of tape is then laid down over the tabs and therebetween to anchor the wire in place during extraction to provide an internal lead for the inductance.

PATENTEU W28 |97| FIG.I

INVENTOR: EDWIN C. RECHEL ELECTRICAL INDUCTANCE AND METHOD BACKGROUND AND SUMMARY OF THE INVENTION In the providing of coils, such as automobile ignition coils, it is necessary to provide both internal and external leads. In the past, the internal lead has posed a problem. Varied, as it is within the annular core, fishing with a hook like a button hook, but on smaller scale, has been employed. In some cases this results in destroying a portion of the coil and thus the inductive value is changed.

According to the instant invention, this problem is uniquely solved through the provision of novel slits within the coil form core piece of the inductance-the lead-in wire being stretched between these tabs and anchored firmly in place. This permits the ready extraction of a suitable length of internal lead wire without the likelihood of disturbing the windings proper.

DESCRIPTION OF THE DRAWINGS The invention is described in conjunction with the accompanying drawing, in which FIG. 1 is a fragmentary perspective view of a coil form employed in the practice of the invention and showing the novel slits and tabs;

FIG. 2 is a view similar to FIG. 1 but showing the coil form of FIG. 1 in alater stage of manufacture, but still intermediate to the end product--a portion only of the lead-in wire being associated with the coil form;

FIG. 3 is a view similar to FIG. 2 and showing the coil form in a yet further stage of development; and FIG. 4 is a coil form of FIGS. 1-3 in its completed form, i.e., in a form suitable for overwinding to provide the ultimate inductance.

In the practice of the invention, I start with a tubular coil form such as is seen in FIG. I and designated generally by the numeral 10. Although a cylindrical type form is illustrated, it will be appreciated that other cross-sectional shaped may also be advantageously employed in the practice of the invention. Illustrative of alternative forms are the conventionally employed square and rectangular tubes.

The tube defines an outer perimetric wall 11 which has been slit at a number of longitudinally spaced apart points as at 12, 13, 14, 15, etc. It will be noted that the slits are generally U-shaped and are oppositely oriented. For example, the tabs 16 and 17 associated with the slits 12 and 13, respectively, fold out toward opposite ends of the tube 10.

The tabs 16 and 17 constitute a pair which ultimately will be located within a given inductance. Tabs 18 and 19, for example, are associated respectively with the slits 14 and and these constitute yet another pair. It will be noted that the tab 18 corresponds to the tab 12 while the tab 19 corresponds to the tab 16. Each pair of tabs ultimately will constitute one induetance unit and normally 10 units can be derived from a given tube or stick." Thus, I provide 10 pairs of tabs and it will be appreciated that the entire tube or stick remains intact until the inductance is completed-as by gang winding. After that, the stick is transversely severed into a plurality of discrete units. Gang winding is illustrated in my prior U.S. Pat. No 3,373,390.

Advantageously, the first step in the practice of my invention is to equip a tube 10 with the tabs 1649, etc. of the form seen in- FIG. 1. Generally, the tube 10 is constructed of a pinrality of layers of spirally wound paper so that slitting is easily achieved.

Each slit is generally U-shaped but preferably departs therefrom to provide an essentially trapezoidal tab. For example, the tabs 16 and 17 are seen to have wider free edges 20 and relatively narrower connective edges 21. Still further, the slits l2 and 13 of a given pair are offset laterally relative to each other so that opposite sides of the tabs in a given pair are in alignment. This is illustrated in FIG. I by the chain line 22 which extends axially of the tube 10 and from the lower comer 23 or the tab 16 to the upper comer 24 of the tab 17. Because of this-arrangement, a wire portion lying on the tube 10 in the position of the chain line 22 will come very close to lying axially of the tube and not only is anchorage facilitated but made more efiective thereby.

After the tube has been provided with slits and tabs of the character seen in FIG. 1, the same is mounted on a winding arbor and positioned below a plurality of spools of wire (not shown). One of the wires from the various spools is illustrated as at 25 in FIG. 2. This wire is applied to the form 10 in a position so as to overlie the opening provided by the slit 13. Advantageously the portion of the wire 25 that overlies the opening 26 made available when the tab 17 is pivoted outwardly to the position seen in FIG. 2 is immediately adjacent the free edge 27 of the opening 26. This is advantageous because at a subsequent stage when the tube is transversely severed, the wire 25 is readily available for extraction.

To insure that the wire 25 is properly positioned and available for winding, an elongated piece of adhesive tape 28 is applied to the coil form 10. This not only overlies the wire 25 but all of the other wires employed in connection with other pairs of tabs, viz, 18, 19, etc.

Once the wire 25 is anchored-and if there is any free end as at 25a, the same can be trimmed at this timethe tube is rotated to provide a plurality of turns over the opening 26, in the form seen in FIG. 3. In FIG. 3, it will be notedthat there are three turns 29 pivoted in addition to the initial partial turn 30. The turn 30 is the portion of the wire immediately adjacent to free edge 27 of the opening 26, but spaced inwardly therefrom about one-fourth inch. The remaining turns 29 are spaced apart from the turn 30 and adjacent the throat part of the opening 26. This structure is conveniently achieved through rotating the tube 10 three times. After that, the wire 25 is turned approximately about the comer 24 of the tab l7-to assume the position designated 22' in FIG. 3. This corresponds to the chain line position 22 indicated in FIG. I. Thereafter the free end of the wire 25 is again turned about 90 (and about the corner 23 of the tab I6) to develop the transversely extending length of wire 31 (still referring to FIG. 3).

At this juncture in the practice of the invention, the tube 10 is translated, i.e., moved longitudinally and a succeeding tube placed adjacent thereto. Thus, the free end 31 is adapted to overlie the successor tube (see FIG. 4). At this point in time, an adhesive strip 32 is laid down on the tube 10 to overlie the length of wire 22' and the tabs 16 and 17. In doing this, the tabs 16 and 17 are folded downwardly into the corresponding slits 12 and 13.

At the same time the tape 32 is laid down, a tape 128 is applied to the tube 110 and the cycle continued. Prior to rotating the coil 110, the free end 31 is severed as at 31a and the tube 10 removed from the gang winding apparatus.

Thereafter the tube 10 is subjected to further winding, the stub lead 31b being attached to relatively finer, i.e., smaller diameter wire which is then wound (with suitable interleaving) about the tube 10 to provide the completed inductance. The overwound tube 10 is then subjected to transverse severing at a line near the free edge 27 of the opening 26, i.e., within the approximate A-inch spacing between edge 27 and wire portion 30. Thus, when it becomes necessary to provide an internal lead, the wire 25 in the portion thereof immediately adjacent the free edge 27 can be readily extracted. If a longer lead-in is required, and this is usually the case, further pulling on the wire 25 uncoils the turns 29. However, because of the arrangement of the tape 32, the wire portion 22' and the tabs 16 and 17, only a certain length of the wire 25 can be removed-the portion preceding the portion 22'. The portion 22 is held securely by the tape 32. Thus, there is no possibility of disturbing the operational windings of the inductance provided by the fine wire connecting to the end 31b. By having pressure sensitive tape applied over a portion of the winding, i.e., a portion of the lead wire, the lead wire is so secured that the lead wire will break before an open circuit can occur.

I claim:

1. An electrical inductance comprising a relatively elongated tubular coil form equipped with an outer wall, said outer wall being provided with a pair of longitudinally spaced apart oppositely oriented generally U-shaped slits providing generally U-shaped tabs, 21 lead-in wire wound on said fonn, said lead-in wire having a starting end and a connective end, a portion of said wire adjacent said starting end being positioned under one tab and a portion of said wire adjacent said connective end being positioned under the other tab, an intermediate portion of said wire extending generally axially between said tabs, and tape overlying said intermediate portion and tabs.

2. The inductance of claim 1 in which each tab is generally trapezoidal in shape to provide a narrower throat connecting the tab to said wall than the tab opposite free edge, said tabs being laterally offset relative to each other.

3. The inductance of claim 2 in which one of said tabs is positioned adjacent an end of said coil form.

4. A method of constructing an electrical inductance comprising the steps of slitting a relatively elongated tube at a plurality of pairs of longitudinally spaced points, each of said slits being generally U-shaped and providing a tab foldable outwardly from the tube, a first tab of each pair being foldable outwardly toward one end of the tube and a second tab being foldable outwardly the other end of the tube, folding each of said tabs outwardly to provide an opening in the tube, fixing one end of a length of wire to said tube, winding a plurality of turns of conductor wire on the tube above the opening provided by one of the tabs of each pair of associated tabs, thereafter turning the free end of said wire about said one tab and generally longitudinally toward the other tab of the pair of associated tabs, turning the free end of said wire about said other tab, and applying a strip of adhesive tape generally longitudinally along said tube above said tabs to force the tabs downwardly and overlie the portion of said wire between the tabs.

5. The method of claim 4 in which wire is severed adjacent the portion turned about said other tab to provide a connection for winding said tube with further wire, the initial turn in said plurality being spaced from the remainder to provide a readily accessible lead-in, and transversely severing said tube adjacent said initial turn. 

1. An electrical inductance comprising a relatively elongated tubular coil form equipped with an outer wall, said outer wall being provided with a pair of longitudinally spaced apart oppositely oriented generally U-shaped slits providing generally U-shaped tabs, a lead-in wire wound on said form, said lead-in wire having a starting end and a connective end, a portion of said wire adjacent said starting end being positioned under one tab and a portion of said wire adjacent said connective end being positioned under the other tab, an intermediate portion of said wire extending generally axially between said tabs, and tape overlying said intermediate portion and tabs.
 2. The inductance of claim 1 in which each tab is generally trapezoidal in shape to provide a narrower throat connecting the tab to said wall than the tab opposite free edge, said tabs being laterally offset relative to each other.
 3. The inductance of claim 2 in which one of said tabs is positioned adjacent an end of said coil form.
 4. A method of constructing an electrical inductance comprising the steps of slitting a relatively elongated tube at a plurality of pairs of longitudinally spaced points, each of said slits being generally U-shaped and providing a tab foldable outwardly from the tube, a first tab of each pair being foldable outwardly toward one end of the tube and a second tab being foldable outwardly the other end of the tube, folding each of said tabs outwardly to provide an opening in the tube, fixing one end of a length of wire to said tube, winding a plurality of turns of conductor wire on the tube above the opening provided by one of the tabs of each pair of associated tabs, thereafter turning the free end of said wire about said one tab and generally longitudinally toward the other tab of the pair of associated tabs, turning the free end of said wire about said other tab, and applying a strip of adhesive tape generally longitudinally along said tube above said tabs to force the tabs downwardly and overlie the portion of said wire between the tabs.
 5. The method of claim 4 in which wire is severed adjacent the portion turned about said other tab to provide a connection for winding said tube with further wire, the initial turn in said plurality being spaced from the remainder to provide a readily accessible lead-in, and transversely severing said tube adjacent said initial turn. 